KR102394238B1 - Method for treating and feeding natural gas to an apparatus for generating power in order to propel a ship - Google Patents

Abstract

The invention relates to the transfer of natural gas in a ship 1 from a liquefied gas storage tank 2 on the one hand to energy production equipment 4 , 6 and on the other hand from a liquefied gas storage tank 2 to a burner of the energy production plant. A method for processing and conveying to (5), the method sequentially feeding into energy production equipment (4, 6), wherein natural gas is passed through phase separators (11a, 11b), whereby the natural gas Among them, the heavy portion containing the hydrocarbon with the longest carbon ring is returned to the tank 2 in the form of condensate, and the light portion containing the hydrocarbon with the shortest carbon ring is transferred to the energy production equipment 4 and 6 , supplying it to energy generating equipment; and recovering the heavy portion of natural gas, wherein the heavy portion of natural gas is passed from the tank (2) to the burner (5) bypassing the phase separators (11a, 11b) It relates to a method comprising a; recovering.

Description

METHOD FOR TREATING AND FEEDING NATURAL GAS TO AN APPARATUS FOR GENERATING POWER IN ORDER TO PROPEL A SHIP

The present invention relates to the field of ships propelled by natural gas.

More particularly, the present invention relates to methods and systems for processing and supplying natural gas from liquefied gas storage tanks to energy production equipment, such as combustion engines.

Vessels including combustion engines for propelling the vessel by supplying natural gas are known in the art. For these combustion engines to work properly, combustible natural gas with certain properties must be used. In particular, in general, natural gas containing a methane number greater than or equal to the standard set by the combustion engine manufacturer should be used, because gases with too low a methane number may not burn properly and may cause a knocking phenomenon.

In order to ensure that the natural gas supplied to the engine has a methane number higher than the standard, in the prior art, a phase separator that allows heavy hydrocarbons in natural gas to return to the storage tank in a condensed form is mounted on the engine supply circuit it is common to do

However, heavy hydrocarbons collected in the storage tank accumulate in the tank. Accordingly, as the amount of gas in the tank runs out, a residue of heavy hydrocarbons that cannot be used for ship propulsion remains.

The idea underlying the present invention is to provide a method and system for processing and supplying natural gas from a liquefied gas storage tank to energy production equipment such as a combustion engine for ship propulsion, which can solve the problem of accumulation of heavy hydrocarbons at the bottom of the tank. is to suggest

According to one embodiment, the present invention provides a method for processing and transporting natural gas in a ship from a liquefied gas storage tank on the one hand to an energy production equipment and on the other hand a burner of an energy production plant, said method comprising: Sequentially,

- As a step of supplying to energy production equipment, in the step of supplying to the energy production equipment, natural gas is delivered through a phase separator, so that a heavy portion containing hydrocarbons having the longest carbon ring among the natural gas is tanked in the form of condensate and allowing the light fraction comprising hydrocarbons having the shortest carbon ring to be delivered to the energy production equipment; and after that

- recovering a heavy portion of natural gas, wherein the heavy portion of natural gas is passed to the burner in the tank bypassing the phase separator.

Thus, by bypassing the phase separator, a heavy portion of the natural gas can be removed by being returned to an energy production facility equipped with a burner.

According to some embodiments, such a method may include one or more of the following features.

- the method comprises the step of monitoring a variable indicative of the methane number of the natural gas during the step of feeding it to the energy production equipment.

- the method comprises an automatic switchover to the step of recovering the heavy portion of the natural gas and/or a warning signal is generated if a parameter indicative of the methane number of the natural gas being delivered exceeds a threshold.

- the variable indicative of the methane number of said natural gas conveyed is measuring the flow rate of the light portion of natural gas downstream of said phase separator and/or measuring the temperature of evaporated natural gas collected in said tank and/or condensate This is determined by measuring the frequency and/or level of emptying of the collection vessel.

According to one embodiment, the present invention provides a system formed on a ship for processing and transporting natural gas, on the one hand, from a liquefied gas storage tank to energy production equipment and on the other hand to a burner of an energy production plant, said The system is

- a primary supply circuit for the supply to said energy production equipment, said primary circuit being equipped with a phase separator, said phase separator being connected on the one hand to a return pipe downstream, whereby the carbon ring in said natural gas is the most to the energy production equipment so that the heavy portion of the natural gas comprising long hydrocarbons is returned to the tank in the form of condensate and, on the other hand, conveying the lighter portion of the natural gas comprising the hydrocarbon with the shortest carbon ring. a primary supply circuit connected to a subsequent conveying tube; and

- a secondary supply circuit for supply to said burner, said secondary circuit comprising a secondary supply circuit bypassing said phase separator.

According to some embodiments, such a system may include one or more of the following features.

- said primary circuit comprising, upstream of said phase separator, at least one circuit portion shared with said secondary circuit, which permits forced evaporation of said liquefied natural gas and is designed to collect evaporated natural gas in said tank include

- the part of the circuit common to the primary and secondary circuits, which opens towards the bottom of the tank, comprises a pump and a suction oil pipeline provided with a forced evaporation facility for converting the liquefied natural gas into a stream of gas; .

- A circuit part common to the primary and secondary circuits comprises an oil pipeline open to the top of the tank for collecting the natural gas evaporated in the tank.

- the part of the circuit common to the primary and secondary circuits, at the downstream boundary part, of the second circuit, in which a switchable three-way connection member is formed so that the part of the circuit in common leads to the inlet of the phase separator or to the burner to be selectively linked as part of it.

- a gas heating installation is installed in the secondary circuit for the supply to the burner;

- the primary circuit for supplying natural gas to the energy production equipment comprises a compressor located downstream of the phase separator.

- the system comprises a device for monitoring a parameter indicative of the methane number of the delivered liquefied natural gas;

- a device for monitoring a variable indicative of the methane number of the conveyed liquefied natural gas is a sensor for measuring the flow rate in a conveying pipe leading towards the energy production equipment and/or measuring the temperature of the evaporated natural gas collected in the tank and/or a sensor for measuring the level of condensate in the condensate collection vessel and/or a counter for measuring the frequency with which the condensate collection vessel is emptied.

- the monitoring device is designed to operate on a switchable three-way connecting member and/or to generate a warning signal to direct the natural gas towards the burner if a parameter indicative of the methane number of the conveyed liquefied natural gas exceeds a threshold.

According to one embodiment, the present invention also provides a ship comprising a liquefied gas storage tank, energy production equipment, and an energy production facility provided with a burner and the natural gas processing and delivery system described above.

According to some embodiments, such a vessel may include one or more of the following features.

- The energy production equipment is for propulsion of the vessel.

- The energy production equipment is a hetero fuel diesel/natural gas combustion engine.

- The liquefied gas storage tank is a tank with a membrane.

- said tank is a storage tank with atmospheric pressure.

According to an embodiment, the present invention also provides a method for filling the tank of a vessel as described above, in which way fluid is transported from a floating or offshore storage facility via insulated oil pipelines towards the tank of the vessel.

According to one embodiment, the present invention also relates to a system comprising the above-described vessel, wherein insulated oil pipelines connected to connect the tank installed in the hull of the vessel to a floating or offshore storage facility, the floating or offshore storage facility and a pump for driving a stream of fluid from a storage facility through the adiabatic pipelines to the tank of the vessel.

The present invention, and further objects, details, features and advantages of the present invention, will become more apparent from the following description of specific embodiments of the invention, which are described for purposes of illustration only and not limitation, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 schematically shows a natural gas processing and delivery system in a ship.
FIG. 2 shows the system of FIG. 1 , in which the paths of the supply of natural gas to the energy production equipment for propulsion of ships and the supply of natural gas to the energy production equipment for power generation are highlighted with bold lines.
FIG. 3 shows the system of FIG. 1 , wherein the path of natural gas to energy production equipment for power generation is highlighted with bold lines.
FIG. 4 depicts the system of FIG. 1 with the path of natural gas to a burner of an energy production facility for recovering and utilizing a heavy portion of natural gas highlighted in bold.
FIG. 5 shows the system of FIG. 1 , in which the path through which the natural gas evaporated in the tank travels towards the burner of the energy production facility is highlighted by bold lines.
FIG. 6 shows the system of FIG. 1 , wherein the path of natural gas during the implementation of the tank heating method is highlighted with bold lines.
7 shows a vessel equipped with a gas storage tank and energy production equipment supplied with natural gas for propulsion of the vessel.

In this specification and claims, the terms "upstream" and "downstream" refer to the direction in which the natural gas circulates.

7 shows a propulsion unit comprising one or more liquefied natural gas storage tanks 2 and one or more energy production device items 4 selected from a combustion engine, fuel cell, or gas turbine supplied with natural gas. The equipped ship 1 is shown. The vessel 1 may be a methane tanker for transporting liquefied natural gas, but is not limited thereto and may be a tanker for other uses. For example, it may be a merchant ship, a passenger ship, a fishing vessel, and the like.

1 shows a natural gas storage tank 2 and a system 3 provided on a ship 1 for the treatment and transport of natural gas. The natural gas processing and delivery system 3 supplies natural gas to the energy production equipment 4 of the propulsion unit as shown in FIG. 2 , or to the burner 5 as shown in FIGS. 4 , 5 , and 6 . provided for supplying natural gas or, optionally, suitable for supplying natural gas to additional energy production equipment such as a gas turbine 6 of a combustion engine, fuel cell or electric generator as shown in FIGS. 2 and 3 . do.

Tank 2 is a closed, insulated tank suitable for storing liquefied natural gas (LNG). The tank 2 may in particular be a tank of the type consisting of membranes capable of storing liquefied natural gas at atmospheric pressure.

The energy production equipment 4 of the propulsion unit is selected from among combustion engines, fuel cells and gas turbines. If the energy production equipment 4 is a combustion engine, the engine may be a hybrid engine powered by diesel/natural gas. These engines 4 may operate in a diesel mode in which only diesel is supplied, or may operate in a natural gas mode. In the case of the natural gas mode, the main fuel may include natural gas or a trace amount of diesel for combustion ignition.

An output shaft associated with the mechanical energy generated by the energy production equipment 4 of the propulsion unit engages one or more screws for propulsion of the vessel, or with an alternator to convert the mechanical energy into electrical energy. It can be coupled, in which case the generated electrical energy is used to drive an electric motor coupled to a screw for propulsion of the vessel. In the latter case, the engine in the case of using a combustion engine may be a DFDE-type engine, which is an abbreviation of Dual Fuel Diesel Electric.

The energy production equipment 6 for power generation can be, for example, a diesel/natural gas heterogeneous fuel combustion engine of the DFDE type, a fuel cell or a gas turbine.

The burner 5 is provided inside the energy production facility. The energy production plant may in particular comprise a boiler for steam production. The steam may be generated for use in a steam turbine for energy production and/or for supply to the heating network of the vessel 1 .

2 shows two circuits for the supply to each of the energy production equipment 4 and the energy production equipment 6 for electricity generation of the propulsion unit. Hereinafter, the circuit for the supply to the energy production equipment 4 of the propulsion unit will be referred to as a "primary circuit", and the circuit for the supply to the energy production equipment 6 for electricity generation will be referred to as a "secondary circuit". The primary circuit can also be used to deliver natural gas to the secondary circuit and vice versa, with this arrangement providing redundancy of supply to the energy production equipment 4 , 6 and thus preventing potential malfunctions. can prepare

The primary circuit comprises an intake pipeline 7a that opens towards the bottom of the tank 2 and is supplied by a pump 8a. The suction oil pipe 7a carries liquefied natural gas in a three-way connection 23, in which the suction oil pipe 7a is, on the one hand, a forced evaporation installation, also called an evaporator ( A valve 123 connected to the inlet of 9a) is connected to the oil pipeline 24 and, on the other hand, to an oil pipeline 25 having a valve 223 connected to an atomizer 10a. The forced evaporation facility 9a allows the conversion of liquefied natural gas into one stream of gas. The outlet of the forced evaporation plant 9a is connected by a pipe 26 to carry the gas stream towards the atomizer 10a. The atomizer 10a may inject the liquefied natural gas collected upstream of the forced evaporation facility 98a into a gas stream obtained at the outlet of the forced evaporation facility 9a. Accordingly, the atomizer 10a causes the gas stream to cool so that the heaviest hydrocarbons, ie the hydrocarbons with the longest carbon rings and the highest evaporation temperature, are condensed. The gas stream is generally cooled to below -100°C.

A gas stream full of floating natural gas droplets leaves the atomizer 10a and is conveyed through an oil pipeline 27 to a phase separator 11a. A phase separator 11a, often called a mist separator, allows the liquid phase to be separated from the gas phase. The liquid phase consists of the heavy portion of natural gas containing heavy hydrocarbons, ie hydrocarbons with the longest carbon rings. The heavy portion of the natural gas is delivered in the form of condensate to the storage tank 2 via a condensate return pipeline 12a. The condensate return oil pipe 12a is provided with a condensate collection container 72a that is emptied when the height of the condensate therein reaches a limit value.

The gas phase, which consists of the light fraction of natural gas, i.e., the fraction comprising hydrocarbons with the shortest carbon rings, is passed through an oil pipeline 28 to a gas heating appliance 13 which heats the gas phase, typically to 30°C. is transmitted These gas heating installations 13 are generally gas/liquid or gas/gas heat exchangers. Here, the gas heating installation 13 is provided with a recirculation loop 29 .

Finally, at the outlet of the gas heating installation 13a , the gas stream is conveyed via an oil pipeline 30 towards the energy production equipment 4 of the propulsion unit.

Likewise, the secondary circuit comprises a suction oil pipe 7b which opens towards the bottom of the tank 2 and is supplied by a pump 8b. The suction pipeline 7b allows the liquefied natural gas to be conveyed to the forced evaporation plant 9b and the two atomizers 10b, 31 . To this end, the suction oil pipe 7b is connected via a three-way connection 32 , on the one hand, to an oil pipe 33 provided with a valve 132 leading to the atomizer 31 , and on the other hand a valve 232 . is provided and connected to an oil pipe 34, which itself is connected to a three-way connection 35, wherein the three-way connection 35 is connected to the oil pipe 34, on the one hand, via the oil pipe 36, the valve 135 It is connected to the provided atomizer 10b, and on the other hand, through the oil pipe 17, the valve 235 is connected to the inlet of the provided forced evaporation facility 9b.

The outlet of the forced evaporation facility 9b is connected to the atomizers 10a, 31 by a series of oil pipelines 37, 38, 39, so that liquefied natural gas is sprayed to condense the heaviest hydrocarbons. The gas stream from the atomizer 31 is conveyed through the oil pipeline 40 to the inlet of the phase separator 11b.

Likewise, the phase separator 11b allows the liquid phase to be separated from the gas phase and the condensate returns to the tank 2 via the condensate return pipeline 12b. The condensate return pipeline 12b is provided with a vessel 72b for collecting condensate, which vessel 72b is emptied regularly when the condensate height reaches a threshold.

On the other hand, at the outlet of the phase separator 11b, the gaseous phase composed of the light fraction of natural gas is conveyed via a gaseous oil pipeline 42 to one or more compressors 16a, 16b arranged in parallel. In order for the gas stream to be conveyed in parallel to the plurality of compressors 16a, 16b, the oil pipeline 42 has one or more multi-way connections 43 leading to the oil pipelines provided with valves 143, 243. will be prepared Referring to Figure 2, the gas stream is conveyed through only one of the two compressors 16a, 16b. However, a gas stream may pass in parallel through the two compressors 16a, 6b, depending on the reference flow rate for feeding the energy production equipment 4 or 6 .

For example, the compressors 16a , 16b provide a gas stream at a pressure compatible with the specifications of the energy production equipment 6 supplied with natural gas, for example at an absolute pressure of 5 to 6 bar for a combustion engine of the DFDE type. These are multi-stage compressors that allow heating and compression. Compressors 16a, 16b may be positive-displacement compressors, centrifugal compressors or compressors compatible with the supply pressure of the inlet side of a combustion engine, fuel cell or gas turbine.

Advantageously, the system 3 can be provided with an anti-surge protection device, which protects the compressors 16a, 16b against velocities with low volumetric flow rates on the inlet side. it is for This arrangement comprises, on the outlet side of the compressors 16a and 16b, a recirculation loop 44 that allows a portion of the compressed gas stream to return upstream of the compressor 16 . The recirculation loop 44 is provided with valves 18a , 18b capable of controlling the flow rate in the recirculation loop 44 . In this embodiment, the recirculation loop 44 is connected to the oil pipeline 14, this arrangement will be described in more detail later.

The gas stream from the compressor(s) 16a, 16b is conveyed to a cooling device 19 which brings the temperature of the gas stream to a reference temperature. If the system comprises several parallel compressors 16a, 16b, the outlets of the compressors 16a, 16b are connected with the inlet of the cooling device 19 via three-way connections 45,63.

Finally, the gas stream from the cooling device 19 is conveyed via an oil pipeline 46 to the energy production equipment 6 of the electric generator. It should be noted that the oil pipe 46 is provided with a three-way connection 47, the two outlet paths of the three-way connection 47 are provided with valves 147 and 247, so that the gas stream is provided with the energy of the electric generator. to be selectively guided towards the production equipment 6 and/or towards the energy production equipment 4 of the propulsion unit.

It should also be noted that, in this embodiment, a compressor is not provided in the primary circuit for supplying the energy production equipment 4, unlike the secondary circuit, which is the primary circuit and the suction oil pipe 7a of the primary circuit. This is because the pump 8a for supply to the furnace can supply a pressure that meets the operating conditions of the energy production equipment 4 .

FIG. 3 shows that the gas is conveyed through the secondary circuit when natural gas evaporated from the storage tank is included in the secondary supply circuit for supply to the energy production equipment 6 .

To this end, the system 3 comprises an oil pipeline 71 which opens to the top of the tank 2 . The three-way connection part 70 connects the oil pipe 71 that is opened to the upper part of the tank 2, the secondary circuit through the oil pipe 48 provided with the valve 170, and the valve 270 and a part of the heating circuit. It is connected to the oil pipeline 49 to be formed. The reason for this will be explained in detail later. The three-way connection 70 and the valves 170 , 270 form a switchable three-way connection member.

In addition, the oil pipeline 48 is connected to the oil pipeline 14 via a three-way connection 50 . The three-way connection part 50 connects the oil pipe 14 to the oil pipe 51 provided with the valve 150 and forming part of the heating circuit, and the oil pipe 48 provided with the valve 170 . The three-way connection 50 and the valves 150 , 170 also form a switchable connection member.

The oil pipe 14 is connected to the secondary circuit through a three-way connector 54 that connects the outlet of the atomizer 10b and the oil pipe 14 to the inlet of the atomizer 31 . Accordingly, the gas evaporated from the tank 2 leaves the forced evaporation facility 9b before being conveyed to the second atomizer 31 and is contained in the gas stream, but by injecting the liquefied natural gas into the gas stream, the phase separator It also has the function of controlling the temperature of the gas stream entering (11b). Accordingly, the secondary supply circuit comprises, in its upstream part, a path for conveying the evaporated natural gas collected in the tank 2 , and a path for forced evaporation of the natural gas.

Such a route for transporting the vaporized gas in the tank is particularly suitable when the liquefied natural gas is stored at ambient temperature, as a result of which significant spontaneous evaporation occurs.

4 and 5 show a route for supplying natural gas to the burner 5 . 4 shows the path of the forced evaporation of natural gas, while FIG. 5 shows the path of the evaporated natural gas collected in the tank 2 . It should be noted that in both cases the circuit for the supply to the burner 5 bypasses the phase separator 11b so that the energy contained in the heavy portion of the natural gas can be recovered.

In FIG. 4 , the supply circuit for the supply to the burner 5 comprises a circuit part in common with the secondary circuit. This shared circuit portion allows the liquefied natural gas to be forced to evaporate, and includes a suction oil pipe 7b supplied by a pump 8b, a forced evaporation facility 9b, and optionally an atomizer 10b.

Downstream of the forced evaporation installation 9b , the processing and conveying system 3 comprises a three-way connection 55 , which is connected to the outlet of the forced evaporation installation 9b by a valve 155 . Natural gas bypassing the phase separator 11b and connecting to a series of oil pipelines 38 , 39 , 40 provided and connected to the phase separator 11b and also provided with a valve 255 , thereby bypassing the phase separator 11b . allows the heavy portion of the burner (5) to be recovered and used. The switchable connecting element thus formed thus allows the effluent from the forced evaporation plant 9b to be selectively conveyed towards the phase separator 11b or the burner 5 .

Oil pipeline 56 carries the gas stream from the forced evaporation plant towards the gas heating plant 57 . This gas heating installation 57 is, for example, a gas/liquid or gas/gas heat exchanger. Here, the gas heating installation 57 is provided with a recirculation loop 58 . This gas heating installation 57 allows the gas phase to be heated upstream of the burner 5 to a reference temperature of 30 DEG C in bulk. At the outlet from the gas heating installation 57 , oil pipelines 68 , 59 carry the gas towards the burner 5 .

In FIG. 5 , the supply circuit for the supply to the burner 5 comprises another circuit part which is shared with the secondary circuit. The shared circuit portion allows the natural gas vaporized in the tank 2 to be collected. This shared circuit portion consists of an oil pipe 71 that opens to the top of the tank 2 , an oil pipe 48 connected to the oil pipe 71 by a three-way connection 70 , and an oil pipe 48 that is connected to the oil pipe 71 by a three-way connection 50 . and an oil pipeline (14) connected to (71). Pipeline 14 also has a three-way connection 60 that connects oilline 14 to a series of pipelines 39,40 running towards phase separator 11b and valves 143,243, and of natural gas. The phase separator 11b is bypassed so that the heavy part can be recovered and used in the burner 5 , and it is connected to the oil pipeline 56 provided with a valve 160 .

Thereafter, as detailed above with reference to FIG. 4 , oil pipeline 56 carries the gas stream towards gas heating installation 57 , and then at the outlet of gas heating installation 57 , oil pipelines 58 , 59 . ) carry the gas towards the burner (5).

It should be noted that although the path of the vaporized natural gas in the tank 2 and the path of the forced vaporization of the natural gas are shown through two figures, this is for the sake of understanding, and to convey the natural gas to the burner 5 It is also possible to use two paths at the same time for

Advantageously, the natural gas treatment and delivery system 3 is provided with a device for monitoring a parameter indicative of the methane number of the liquefied natural gas being delivered. Methane number is a measure of the ability of a gas mixture to withstand the undesirable phenomenon of knock, and ranges from 0 to 100. Methane number depends on the composition of natural gas. Pure methane has a methane number of 100. This number decreases as the proportion of heavier hydrocarbons such as propane and/or butane and/or pentane increases.

Such a device for monitoring a variable indicative of the methane number of natural gas may include one or more flow meters for measuring the flow rate of the light fraction of natural gas, for example downstream of one or two phase separators 11a , 11b in oil pipeline 42 . may include These flow rates represent the methane number of the liquefied natural gas being transported. This is because, under stable conditions at a constant pumping flow rate, the flow rate tends to decrease as the tank 2 is emptied and the concentration of heavy hydrocarbons increases.

Alternatively or in addition to this, it is possible to arrange a temperature sensor in the oil pipeline 48 for carrying the collected vaporized gas in the tank 2 , for example to measure the temperature of the vaporized gas. This is because the higher the temperature of the vaporized gas, the higher the proportion of heavy hydrocarbons contained in the tank, because it is closer to the end of the journey.

Also, alternatively or in addition to this, recording the frequency with which the at least one condensate collection vessel (72a, 72b) is emptied and/or monitoring how the height of the condensate in the at least one vessel (72a, 72b) changes can do.

The monitoring device also includes a control unit capable of receiving and processing data collected by at least one of the sensors to be described below. The control unit compares the parameter(s) representing the methane number with a reference. Based on this comparison, the control unit generates a warning or a heavy portion of the natural gas is withdrawn from the operating mode in which the natural gas is supplied to the energy production equipment 4 , 6 of the propulsion unit and/or the electric generator so that the energy production plant can be damaged. It is possible to automatically switch to the operating mode conveyed by the burner (5). In a practical situation, when the methane number variable corresponds to a methane number of approximately less than 80, the control unit generates a warning or automatically switches to a mode in which a heavy portion of natural gas is recovered and used.

In an embodiment foreseeing this automatic switching in the operating mode, a monitoring device is provided in one of the three-way connections 55 , 60 for diverting the gas stream towards the burner 5 bypassing the phase separator 11b . A reference signal is transmitted to the above valves 155 , 255 , 160 , 143 , and 243 .

If the energy production equipment is a gas/diesel hetero-fuel combustion engine, the combustion engine of the propulsion unit and/or the electric generator 6 or The fuel cell or gas turbine 4 switches to diesel mode to continue propulsion and/or electricity generation of the vessel.

6 shows the path of natural gas during implementation of the method of heating the tank 2 . This method is carried out when the tank is almost empty, wherein the natural gas remaining in the tank 2 is in gaseous form.

In the implementation of the heating method, natural gas is collected at the bottom of the tank 2 using an oil pipeline 52 that opens into the bottom of the tank 2 .

In the present embodiment described, the oil pipeline 52 which opens into the bottom of the tank 2 is connected to a switchable connecting member 53 , wherein the switchable connecting member 53 allows the gas stream to flow into the bottom of the tank 2 . Filling for filling the tank 2 so that the pipeline 52 is selectively connected to the pipeline 51 in the upstream part of the heating circuit to be collected in the section, or to transport the liquefied natural gas from the shore storage to the tank 2 The oil pipe 52 is connected to the circuit 61 .

In addition, the oil pipeline 51 of the upstream part of the heating circuit is connected downstream of the three-way connection 50 . Valves 170 and 150 allow one of the oil pipelines 51 in the upstream part of the heating circuit, or a pipeline 48 to carry the evaporated gas collected in the tank 2, optionally connected to the pipeline 14. .

Accordingly, the upstream portion of the heating circuit is connected to the inlets of the compressors 16a, 16b by oil pipelines 39, 40, 42, thereby allowing the gas collected at the bottom of the tank to be conveyed to the compressors. The temperature of the gas stream exiting the compressors 16a, 16b to implement the tank 2 heating method is, for example, 50° C. in bulk.

Accordingly, the portion of the circuit comprising at least one of the oil pipelines 14 , 39 , 40 , 42 and the compressors 16a , 16b is a secondary circuit for supplying gas to the energy production equipment 4 , 6 and the heating circuit. is common with Consequently, the design of the system 3 for processing and transporting gases is optimized, and at least one of the compressors 16a, 16b prepares a gas stream for supply to the energy production equipment 4, 6, and the tank (2) Involved in implementing the heating method.

At the outlet of the compressors 16a, 16b, the three-way connections 62, 63 open towards the secondary supply circuit and the oil pipelines 64, 65 provided with valves 162, 163 and the valves 262, 263 The discharge ports of the compressors 16a and 16b are connected to the provided oil pipelines. Said oil pipelines 64 , 65 are connected via three-way connections 66 , 67 to an oil pipeline 56 forming part of the supply circuit for the supply to the burner 5 leading to the gas heating installation 57 . .

Accordingly, to heat the tank 2 , the gas stream passes through both compressors 16a , 16b and heating installations 57 . The temperature of the gas stream leaving the gas heating facility 57 is approximately 80°C.

Furthermore, after exiting the gas heating installation 57, the oil pipeline 68 leads to a three-way connection 69, the surplus part of the gas stream being provided with a valve 169 in the oil pipeline 59. and the remaining gaseous portion is returned to the tank 2 via an oil pipe 49 provided with a valve 269 and forming a return section leading to the tank 2 .

Accordingly, the oil pipe 56 , the gas heating facility 57 , and the oil pipe 68 form a circuit part common to a heating circuit for heating the tank 2 , and a supply circuit for supplying gas to the burner 5 . will understand that As a result, the oil pipelines 64 , 65 have connecting sections allowing the outlets of the compressors 16a , 16b to be connected to a portion of the circuit common to the tank 2 heating circuit and the supply circuit supplying gas to the burner 5 . to form

An oil pipeline 49 forming a return section leading to the tank 2 is connected via a three-way connection 70 to an oil pipeline 71 that opens to the top of the tank 2 . Accordingly, depending on the positions of the valves 170 and 270 , when natural gas needs to be supplied to the energy production equipment 4 , 6 or the burner 5 , the oil pipeline 71 opened to the upper part of the tank 2 is It can be used to collect the vaporized gas in the tank 2 , or to inject hot gas when the tank 2 needs to be heated.

As a result, when the heating method of the tank 2 is implemented, gas is extracted from the bottom part of the tank 2 while the hot gas is injected into the upper part of the tank 2 . Since the hot gas has a tendency to rise to the top of the tank 2 , this arrangement enables thermal stratification of the tank 2 , thereby increasing the efficiency of the tank 2 heating method.

As shown in FIG. 7 , in a conventional manner, by means of suitable connections, loading/unloading oil pipelines for transporting LNG cargo between and with the tank 2 may be connected to the sea or port terminal.

7 shows an example of an offshore terminal including a liquefied natural gas supply station 82 , an underwater oil pipeline 83 , and an offshore installation 81 . The liquefied natural gas supply station 82 is a stationary offshore installation comprising a mobile arm 84 and a tower 85 supporting the mobile arm 84 . A movable arm 84 carries insulated flexible hoses 80 that can be connected to shipping pipelines. This orientable movable arm 84 is applicable to ships of all sizes. A connector (not shown) extends upwardly in the tower 85 . The liquefied natural gas supply station 82 allows the tanks of the vessel 1 to be supplied from the shore installation 81 . The offshore installation 81 comprises liquefied gas storage tanks 86 and connecting pipes 87 connected by submersible pipes 83 to the liquefied natural gas supply station 82 . The submersible tube 83 allows the liquefied gas to be transported between the liquefied natural gas supply station 82 and the offshore installation 81 .

In order to create the pressure necessary for transporting the liquefied gas, pumps provided on the vessel 1 and/or pumps provided on the shore installation 81 and/or pumps provided at the loading and unloading station 82 are used.

Although the present invention has been described with reference to several specific embodiments, it is to be understood that the present invention is not limited to these embodiments and includes all technical equivalents of the described means and combinations thereof falling within the scope of the present invention.

In particular, although in the embodiments described above the vessel comprises only one liquefied natural gas storage tank, the gas treatment and delivery system may be connected to a plurality of storage tanks. In this case, the storage tanks each comprise suction oil pipelines to which the supply is made by pumps and oil pipelines opening to the top and bottom portions of the tank, which are connected to the treatment system circuits as described above.

It should also be noted that the term connecting member is used herein to describe the coupling between a three-way connection and some valves provided with one or more inlet pipelines or one or more outlet pipelines, but the term connecting element is not includes all technical equivalents capable of connecting two inlet pipelines to the outlet pipelines, or one inlet pipeline to two outlet pipelines, wherein the connecting member is also, depending on the situation, for gas from one of the two inlet pipelines. You can choose to advance the stream or to direct the gas stream towards one of the two outlet oil pipelines, to split the inlet gas stream into two outlet streams, or to combine the two inlet gas streams into one outlet gas stream. including means.

The use of verbs such as "comprise" and "comprise" and variations of such verbs does not exclude the possibility of the existence of elements or other steps recited in a claim. The indefinite article "a" used in an element or step also does not exclude the possibility that there may be a plurality of elements or steps, unless otherwise stated.

In the claims, reference signs placed between parentheses shall not be construed as limiting the claim.

Claims (4)

Natural gas in the vessel 1 from the liquefied gas storage tank 2 on the one hand to the energy production equipment 4 , 6 and on the other hand from the liquefied gas storage tank 2 to the burners 5 of the energy production plant A method for handling and transporting, said method comprising:
As a step of supplying to the energy production equipment (4, 6), natural gas is delivered through the phase separators (11a, 11b), so that the heavy portion of the natural gas containing hydrocarbons with the longest carbon ring is in the form of a condensate tank Returned to (2), the light fraction comprising hydrocarbons with the shortest carbon ring is passed to the energy production equipment (4, 6), and a variable indicative of the methane number of the delivered natural gas is monitored. supplying with; and
supplying a heavy portion of natural gas to the burner (5), and when the parameter representing the methane number of the conveyed natural gas exceeds a threshold value, an automatic switch is made to the step of supplying a heavy portion of the natural gas to the burner, , the natural gas is collected in liquid phase in the tank 2 and from the tank 2 bypasses the phase separators 11a, 11b to the burner 5 without passing through the phase separators 11a, 11b. feeding a heavy portion of natural gas to the burner from which it is delivered and from which the heavy portion of the natural gas is removed. delete delete The method of claim 1,
The variable indicative of the methane number of the delivered natural gas is measured by measuring the flow rate of the light portion of the natural gas downstream of the phase separators 11a, 11b, or by measuring the temperature of the evaporated natural gas collected in the tank, or by measuring the condensate The method of claim 1, wherein the frequency of emptying of the collection vessel is determined by measuring the height.

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